Can't register: empty "Register for this Site" box

When I installed, activated and configured WangGuard today, everything went fine. I then logged out of the site where I installed it, http://www.jhwm.net.

When I go to http://www.jhwm.net/wp-admin and then click Register, I see the security questions I created. Looks good, but I doubt most visitors would know to use that process to register for (or log into) the site.

That’s why the site is also running a plugin called Login With Ajax, which provides the “Log In” box with the Register link in the R-hand column. Clicking this Register link gives me a box which is empty except for the words “Register for this Site” in it.